Exam 1 Notes

Exam 1 Notes - NFS 227 Exam 1 Notes -Water: 60-70% of body...

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NFS 227 Exam 1 Notes -Water: 60-70% of body -Fat: 15-25% (varies) 3 States of Water: 1) Solid: Molecules lined up closely together 2) Liquid: Molecules move away from each other but don’t escape 3) Gas: Molecules move so far apart that they escape into air Liquid- 32-212 degrees F (0-100 degrees C) Gas- Steam, Humidity Solid- 39 degrees F- Most Dense, More Organized, Increase volume by 9% -Specific Heat: Amount of heat to raise temp of 1 gram of a substance 1degree C to Kcal -Freezing Point: When a liquid turns into a solid -Melting Point: Solid to Liquid -Boiling Point: Liquid to gas *FP, MP, & BP are all specific temps* -Heat of Fusion: Solidification- Amount of heat removed w/out changing temp -Heat of Vaporization: Amount of heat needed to produce steam Heat of Fusion: 80 cal/ gram Heat of Vaporization: 540 cal/ gram -Endothermic: Absorbing heat -Exothermic: Losing Heat -Specific Heat (1cal/ 1 gram/ 1 degree C) -Vapor Pressure: Pressure of steam trying to escape water, Exceeds atmospheric pressure Question: Does water boil more quickly at Denver, Co or Narragansett town beach? -Denver, b/c the elevation is higher Addition of Solute: -Solute- Sugar or Salt Boiling Point: -Reduce VP -Increases BP Freezing Point: -Interferes w/ a lattice -Lowers FP
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-Surface Tension: Attraction b/w molecules at surface of liquid Functions of water in food: Heat Transfer: Solvent: Chemical Rxn: Boiling Colloidal Dispersion Change in Ph Simmering Suspension Salt Formation Steaming Emulsion Hydrolysis Stewing CO2 Release Braising Food Preservation 1) Dispersions: A) True Solutions B) Colloidal Dispersions C) Coarse Suspensions 1) Unsat Solution- Can dissolve more solute 2) Sat Solution- As much solute in solution as possible 3) Supersat Solution- More solute in solution than theoretically possible B) Colloidal Dispersions: -Continuous & dispersed phases -Hydrophilic vs. Hydrophobic -Polar vs. Nonpolar groups -Sol: Solid in Liquid -Gel: Liquid in Solid -Foam: gas in liquid -Emulsion: Liquid in liquid -Immiscible = 2 Liquids that don’t mix well -Suspensoid: Gas in liquid C) Coarse Suspension: Starch, Flour Chemical Reactions: Ionization- Neutral Molecule-- Electrically charged ions (electrolytes) NaCl-> Na+ Ph = Acids vs. Bases (alkaline) Acid = Donates H+ Base = Provides OH- -Hydrolysis: Breaking down of a bond w/ addition of molecule of H20 -Condensation: Formation of bond w/ loss of molecule of H20
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Water Activity: -Free vs. Bound- Not amt of H20 -Food Preservation Aw= VP of H20 in a Product / (Divided by) VP of pure H20 = 0-.99 Monolayer: Destroy Food (Protein, Sugar) Multilayer: Hydrogen Bonding (Capillaries) Bulk: Micro-organism Growth (Bacteria Grows) *Most bacteria growth inhibited below Aw= 0.91 Absolute Limit = 0.60 Yeasts: Aw = 0.87 Mold: Aw = 0.80 Osmosis: Movement of solvent through a semi permeable membrane from lower to higher solute conc. Ex: Vegetables “sweat” when sprinkled with salt
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Exam 1 Notes - NFS 227 Exam 1 Notes -Water: 60-70% of body...

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